Patent application title: Evidence Tracking

Abstract:

A system uses a large loop antenna, connected with a transceiver operating
below 1 MHz. The loop antenna is deployed from a spool to surround a
crime scene, and may carry indicia communicating that it is a crime scene
boundary. The system interrogates devices, including evidence bags and
badged personnel, as they enter and leave the scene. The system can
optionally log the time of salient events. A second loop antenna can log
evidence bags as they enter a vehicle. The devices can be silenced by the
transceiver and thus collisions can be reduced and avoided among
responses from devices. The system performs "area reads" that would not
be possible if higher RF frequencies were employed.

Claims:

1-11. (canceled)

12. An electrically conductive line comprising a tape bearing printed
indicia visible from a distance, the indicia comprising the words "CRIME
SCENE"m the line being at least 20 feet in length.

13. Apparatus comprising a spool, the spool having wound thereon an
electrically conductive line comprising a tape bearing printed indicia
visible from a distance, the indicia comprising the words "CRIME SCENE"m
the line being at least 20 feet in length.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]This application claims priority from U.S. application No.
60/700,886 filed Jul. 19, 2005, and from U.S. application No. 60/806,748
filed Jul. 7, 2006, each of which is incorporated herein by reference for
all purposes.

BACKGROUND

[0002]It is not easy to keep track of evidence in a crime scene
investigation. It is necessary for each piece of evidence to maintain a
"chain of custody" so that the authenticity of a piece of evidence at
trial can be known. At many crime scenes it is also necessary to maintain
a log of the personnel entering and leaving the crime scene. The
procedures required to maintain the chain of custody and the crime scene
log are detail-oriented and if errors are made it can be a big problem
later.

[0003]It has been proposed to use RFID tags, for example, to try to keep
track of evidence and to assist in logging entry and exit of personnel
from areas. Most RFID tag designs are not very workable for these
purposes, as they are little more than high-tech bar codes that can only
be read by a reader such as a handheld "gun" that is placed into close
physical proximity with a tag to read the tag. At most crime scenes it is
unworkable to try to use close-proximity readers, whether bar-code or
RFID. One cannot, for example, count on a person who is entering or
exiting a crime scene to do so at a location where such a close-proximity
reader is located. Through inadvertence or otherwise, an evidence bag
might enter or exit a crime scene boundary at any point along the
boundary.

[0004]It would be very desirable if a system and method could be devised
that would facilitate RF tracking of salient events at a crime scene,
that would detect entry and exit at all points along a boundary, and that
would more or less continually keep track of who is in the crime scene.

SUMMARY OF THE INVENTION

[0005]A system uses a large loop antenna, connected with a transceiver
operating below 1 MHz. The loop antenna is deployed from a spool to
surround a crime scene, and may carry indicia communicating that it is a
crime scene boundary. The system interrogates devices, including evidence
bags and badged personnel, as they enter and leave the scene. The system
can optionally log the time of salient events. A second loop antenna can
log evidence bags as they enter a vehicle. The devices can be silenced by
the transceiver and thus collisions can be reduced and avoided among
responses from devices. The system performs "area reads" that would not
be possible if higher RF frequencies were employed.

DESCRIPTION OF THE DRAWING

[0006]FIG. 1 shows a typical deployment of the system according to the
invention.

DETAILED DESCRIPTION

[0007]Turning to FIG. 1, what is shown is a typical deployment of the
system according to the invention. A truck or other motor vehicle 16
arrives at a crime scene defined by corpse 15. A spool 13 is removed from
the truck and is placed at a position that lies on a desired crime scene
boundary. An electrically conductive line 12 is unspooled from the spool
13 and is laid out along the surface of the ground along the desired
crime scene boundary, returning to the start to define a complete
boundary. The line is connected to a transceiver 14 about which more will
be said later. The transceiver 14 is optionally equipped with a GPRS,
Edge, EVDO, WiFi, or other WAN interface permitting reporting of events
to distant equipment omitted for clarity in FIG. 1.

[0008]Personnel 18 wears a badge 19, containing a radio tag. The radio
tags employed can, for example, be tags such as those described in U.S.
Pat. No. 7,049,963 entitled "Networked RF tag for tracking freight" and
assigned to the same assignee as the present invention, which patent is
incorporated herein by reference.

[0009]The transceiver 14 can, for example, be a transceiver such as that
described in copending U.S. application No. 60/806,520, filed Jul. 3,
2006 and assigned to the same assignee as the present invention, which
application is incorporated herein by reference. The transceiver can
transmit at, say, a predetermined multiple of 32768 Hertz (the standard
watch crystal frequency) such as 65 kHz or 133 kHz. The transceiver may
have switchable antenna terminals to handle as many as four distinct
antennae. The transceiver can switch from one antenna to the next, and
even if one antenna is not well coupled with a particular tag, very
likely one of the other two antennas will turn out to be well coupled
with that particular tag.

[0010]The typical steps of deployment, as mentioned above, call for a line
at least twenty feet in length. Each tag, whether on an evidence bag or
on a badge, has a respective identifier and is disposed to receive
queries at a radio frequency no greater than 1 MHz and to emit responses
thereto at a radio frequency no greater than 1 MHz. In the case of an
evidence bag, there is a tag mechanically affixed to the bag. The bag has
an opening and a closure for the opening.

[0011]A first responder at the crime scene will define a first scene of
interest having a perimeter, the scene of interest having an area, the
area exceeding twenty-five square feet, the perimeter extending at least
twenty feet. The conductive line is deployed starting with its first end
at a first point at the perimeter, along the perimeter around the first
scene of interest, and returning with its second end to the first point.
A first apparatus (the transceiver 14) is connected a the first and
second ends of the line. The apparatus operates at a radio frequency no
greater than 1 MHz.

[0012]The first apparatus is operated to emit a query. It is operated to
listen for a response to the query from a tag. In the event of a
response, an identifier is extracted an identifier, and the identifier is
stored in the first apparatus and/or is communicated via a WAN link to
other equipment. A silence request is transmitted with respect to the
identifier.

[0013]The emitting, listening, extracting, storing, and transmitting
steps, are repeated, thereby accumulating a list of identifiers. The
system makes note of times at which the list changes, thereby detecting
events of tags and/or badges entering and leaving the first scene of
interest.

[0014]Later when the crime scene is cleared, the line is removed and
respooled. Still later, the spool is redeployed to a second crime scene
elsewhere.

[0015]The line may be laid upon the ground, or may be suspended from posts
or vegetation or otherwise deployed at waist or chest height.

[0016]Evidence bags can optionally each have a button that permits the tag
to respond differently due to the pressing of the button, in which case
in the event of a response that is different due to the pressing of a
button, what is stored additionally includes information thereof, thereby
detecting events of the pressing of a button on a tag. The button might
mean that the bag has been put into use.

[0017]The evidence bags may each have a motion sensor which, when
triggered, causes the tag to respond differently due to sensed motion, in
which case in the event of a response that is different due to sensed
motion, what is stored additionally includes information thereof, thereby
detecting events of motion of an evidence bag.

[0018]The procedure for use of a bag may include such steps as placing a
first item in a bag affixed to a first tag; closing the closure of the
bag affixed to the first tag; placing a second item in a bag affixed to a
second tag; closing the closure of the bag affixed to the second tag;
removing the first tag and the second tag, and their respective bags,
from the enclosure; and detecting the events of the first and second tags
leaving the scene of interest.

[0019]Badges may also be used. A badge may have a respective identifier
and disposed to receive queries at a radio frequency no greater than 1
MHz and to emit responses thereto at a radio frequency no greater than 1
MHz, in which case the step of making note of times at which the list
changes further detects events of badges entering and leaving the first
scene of interest.

[0020]The evidence bags may optionally each have a sensor sensing a closed
condition of the closure, the sensor causing the tag to respond
differently due to the closed condition, in which case in the event of a
response that is different due to the closed condition, what is stored
additionally includes information thereof, thereby detecting events of
the closure being opened or closed on the bag of a tag.

[0021]The conductive line may comprises a tape bearing printed indicia
visible from a distance, for example the words "CRIME SCENE".

[0022]It will be appreciated that this system can detect entry and exit of
evidence bags and of badges from any direction. There is not a need to
enter and exit at a particular point along the boundary.

[0023]Those skilled in the art will have no difficulty devising myriad
obvious variations and improvements of the invention, all of which are
intended to be encompassed within the claims which follow.